Two-dimensional light-emitting element array device and method for driving the same

ABSTRACT

A dimensional light-emitting element array device is provided. The device comprises a light-emitting element array in which a plurality of three-terminal light-emitting thyristors are arranged in X-Y matrix of N rows×M columns; a plurality of row lines to each thereof an anode of the thyristor on a corresponding row of the matrix is connected; one clock line to which all the row lines are connected; a plurality of row address lines to each thereof a gate of the thyristor on a corresponding row and a 0th column of the matrix is connected; and a plurality of column address lines to each thereof a gate of the thyristor on a corresponding column of 1st-Mth columns of the matrix is connected.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a two-dimensional light-emitting element array device, particularly to a two-dimensional light-emitting element array device using three-terminal light-emitting thyristors. The present invention further relates to a method for driving such a two-dimensional light-emitting element array device.

2. Description of the Prior Art

A two-dimensional light-emitting element array device constituted by arranging a plurality of three-terminal thyristors of PNPN structure in two-dimension have been disclosed in Japanese Patent Publication Nos. 3-200364 and 3-273288, these publications being related to the Japanese Patent applications filed by the present applicant.

The two-dimensional light-emitting array device disclosed in these publications, however, needs at least three light-emitting thyristors and three clock lines for constituting one picture-element, so that there is such a problem that the area of one picture-element is large.

FIG. 1 shows the two-dimensional light-emitting element array device disclosed in Japanese Patent Publication No. 3-273288. In this device, a plurality of light-emitting thyristors are arranged in two-dimension, i.e., in X-Y matrix. Clock lines CK₁-CK₃ which supply clocks φ₁-φ₃ respectively are connected to the thyristor in such a way that each clock line is connected obliquely from the thyristor on upper left to the thyristor on lower right.

In this two-dimensional light-emitting element array device, ON state (light-on state) of the light-emitting thyristor P may be transferred on the device toward the right side or lower side on the drawing. In this case, four light-emitting thyristors enclosed by a dotted-line 10 constitutes one picture-element. Therefore, the area of one picture-element is large, resulting in the low density of picture-elements.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a two-dimensional light-emitting element array device in which the density of picture-elements may be increased.

Another object of the present invention is to provide a method for driving the two-dimensional light emitting element array device.

According to a first aspect of the present invention, a two-dimensional light-emitting element array device comprises a light-emitting element array in which a plurality of three-terminal light-emitting thyristors are arranged in X-Y matrix of N rows×M columns (N≧1, M≧0); a plurality of row lines to each thereof an anode of the thyristor on a corresponding row of the matrix is connected; one clock line to which all the row lines are connected; a plurality of row address lines to each thereof a gate of the thyristor on a corresponding row and a 0th column of the matrix is connected; and a plurality of column address lines to each thereof a gate of the thyristor on a corresponding column of 1st-Mth columns of the matrix is connected; and light-emitting portions of all the thyristors on the 0th column are covered by an opaque material.

A method for driving this device in such a manner that one or more thyristors on a Jth column (1≦J≦M) of the matrix is intended to emit light comprises the steps of: driving a row address line to High-level, which is of a corresponding row of the matrix on which a thyristor to be emitted light is, while driving other row address lines to Low-level; driving a column address line on the Jth column to Low-level, while driving other column address lines to High-level; and driving the clock line to High-level.

According to a second aspect of the present invention, a two-dimensional light-emitting element array device comprises a light-emitting element array in which a plurality of three-terminal light-emitting thyristors are arranged in X-Y matrix of N rows×M columns (N≧1, M≧1); one clock line to which anodes of all the thyristors are connected; a plurality of row address lines to each thereof a gate of the thyristor on a corresponding row of the matrix is connected through a first resistor; and a plurality of column address lines to each thereof a gate of the thyristor on a corresponding column of the matrix is connected through a second resistor.

A method for driving this device in such a manner that a thyristor on a Ith row and Jth column (1≦I≦N, 1≦J≦M) of the matrix is intended to emit light comprises the steps of: driving a row address line on the Ith row to Low-level, while driving other row address lines to High-level; driving a column address line of the Jth column to Low-level, while driving other column address lines to High-level; and driving the clock line to High-level.

According to a third aspect of the present invention, a two-dimensional light-emitting element array device comprises a light-emitting element array in which a plurality of three-terminal light-emitting thyristors are arranged in X-Y matrix of N rows×M columns (N≧1, M≧0); a plurality of row lines to each thereof an anode of the thyristor on a corresponding row of the matrix is connected ; one clock line to which all the row lines are connected; a plurality of row address lines to each thereof a gate of the thyristor on a corresponding row and a 0th column of the matrix is connected; a plurality of column address lines to each thereof a gate of the thyristor on a corresponding column of 1st-Mth columns of the matrix is connected; a first self-scanning type transfer element array for driving the column address lines to High-level or Low-level by self scanning thereof; and a second self-scanning type transfer element array for driving the row address lines to High-level or Low-level by self scanning thereof; and light-emitting portions of all the thyristors on the 0th column are covered by an opaque material.

A method for driving this device in such a manner that one or more thyristors on a Jth column (1≦J≧M) of the matrix is intended to emit light comprises the steps of: driving the column address lines in turn to High-level by the first self-scanning type transfer element array; driving one or more row address lines to High-level, while driving other row address lines to Low-level by the second self-scanning type transfer element array, when the column address line on the Jth column is driven to Low-level; and driving the clock line to High-level.

According to a fourth aspect of the present invention, a two-dimensional light-emitting element array device comprises a light-emitting element array in which a plurality of three-terminal light-emitting thyristors are arranged in X-Y matrix of N rows×M columns (N≧1, M≧1); one clock line to which anodes of all the thyristors are connected; a plurality of row address lines to each thereof a gate of the thyristor on a corresponding row of the matrix is connected through a first resistor; a plurality of column address lines to each thereof a gate of the thyristor on a corresponding column of the matrix is connected through a second resistor; a first-scanning type transfer element array for driving the column address lines to High-level or Low-level by self scanning thereof; and a second-scanning type transfer element array for driving the row address lines to High-level or Low-level by self scanning thereof.

A method for driving this device in such a manner that a thyristor on a Ith row and Jth column (1≦I≦N, 1≦J≦M) of the matrix is intended to emit light comprises the steps of: driving the column address lines in turn to Low-level by the first self-scanning type transfer element array; driving the row address lines in turn to Low-level by the second self-scanning type transfer element array, when the column address line on the Jth column is driven to Low-level; and driving the clock line to High-level.

According to the present invention, the density of picture-elements of the device may be increased, since one light-emitting thyristor constitutes one picture-element.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, aspects and advantages will be better understood from the following detailed description of preferred embodiments of the invention with reference to the drawings.

FIG. 1 shows a conventional two-dimensional light-emitting element array device.

FIG. 2 shows a fundamental structure of a three-terminal light-emitting thyristor.

FIG. 3 shows a first embodiment of the two-dimensional light-emitting element array device of the present invention.

FIG. 4 shows a second embodiment of the two-dimensional light-emitting element array device of the present invention.

FIG. 5 shows a third embodiment of the two-dimensional light-emitting element array device of the present invention.

FIG. 6 shows exemplary driving pulses for a three-phase driving self-scanning type transfer element array.

FIG. 7 shows a fourth embodiment of the two-dimensional light-emitting element array device of the present invention.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

The explanation of a three-terminal light-emitting thyristor will be given in briefly, before various preferred embodiments are described. Generally, LED (Light-Emitting Diode) and LD (Laser Diode) are known as a representative of light-emitting elements. LED constitutes a PN or PIN junction by compound semiconductor such as GaAs, GaP, GaAlAs, and the like, and utilizes a light-emitting phenomenon based on the recombination of carriers injected into the junction to which a forward voltage is applied.

LD has a structure in which a waveguide is provided in LED. When a current larger than a threshold current flows into LD, electron-hole pairs are increased to arise population inversion. Thus, the multiplication of photon due to a stimulated emission is occurred to generate light by means of parallel reflecting mirrors formed by cleavage planes. The light is again fed back to an active layer to cause a laser oscillation, and a laser is emitted from the end surface of the wave guide.

Also, a negative-resistance element (a light-emitting thyristor, a laser thyristor, and the like) is known which has same light-emitting mechanism as that of LED and LD. The light-emitting thyristor constitutes a PNPN structure with compound semiconductor, and is commercially available as a silicon thyristor.

FIG. 2 shows a fundamental structure of a three-terminal light-emitting thyristor. As shown in the figure, a PNPN structure is formed on an N-type GaAs substrate 2. The thyristor has three terminals, i.e., a gate 4, an anode 6, and a cathode 8. The gate 4 serves for controlling an ON voltage, i.e., a turn-on voltage applied to the anode 6. The ON voltage is equal to the voltage, i.e., the sum of a diffusion potential of the PN junction and a voltage drop due to a current necessary for turning-on the thyristor. When the thyristor is turned-on, the voltage of the gate 4 becomes substantially equal to the voltage of the cathode 8. Therefore, if the cathode 8 is connected to the ground, then the gate voltage becomes 0 volt.

FIG. 3 shows a first embodiment of the two-dimensional light-emitting element array device according to the present invention. This device comprises a light-emitting element array in which a plurality of three-terminal light-emitting thyristors are arranged in two-dimension, i.e., in an X-Y matrix of N rows×M columns (N≧1, M≧0). In the figure, the matrix of 4×5 is shown for simplicity of the drawing.

In this device, the anodes of the thyristors on the Ith row (1≦I≦N) of the matrix are connected to a corresponding row line 12 of the Ith row. Each row line 12 is connected to a clock line φ₁ through a corresponding resistor R_(L1), R_(L2), R_(L3), . . . as shown in the figure. The gates of the thyristors on the Jth column (1≦J≦M) of the matrix are connected to a corresponding column address line φ_(v1), φ_(v2), φ_(v3), . . . , respectively. On the other hand, the gates of the thyristors P₁₀, P₂₀, P₃₀, . . . on the 0th column are connected to a corresponding row address lines φ_(h1), φ_(h2), φ_(h3), . . . , respectively. The cathodes of all the thyristors are connected to the ground. Light-emitting portions of all the thyristors P₁₀, P₂₀, P₃₀, . . . on the 0th column are covered by an opaque material (not shown) in order to prevent the emitted light from leaking to the surface of the device.

For the thyristors connected to the same row line 12, when the clock line φ_(I) is driven to High-level, the thyristor having the lowest gate voltage may emit light at the beginning. When the thyristor is turned-on, the gate voltage thereof goes to the voltage of the cathode, i.e., 0 volt, and the anode voltage thereof substantially equals to a diffusion voltage of the PN junction. As a result, the voltage of the row line 12 is fixed to said anode voltage. Therefore, other thyristors connected to the same row line 12 may not turn-on even if the gate voltage thereof goes to Low-level i.e., 0 volt. That is, if the Ith row address line φ_(hI) is at Low-level, the thyristor P_(I0) on the 0th column will preferentially emit light when the clock line φ_(I) is driven to High-level. On the other hand, if the Ith row address line φ_(hI) is at High-level, the thyristor will emit light to which the Jth column address line φ_(vJ) driven to Low-level is connected.

Next, a method for driving the two-dimensional light-emitting element array device shown in FIG. 3 will be explained. It is assumed that any thyristor on the Jth column of the matrix is caused to emit light. First, the 1st-Nth row address lines are driven to High-level or Low-level, respectively, according to light-emission information. Then, the Jth column address line φ_(vJ) selected by scanning is driven to Low-level, and the column address lines other than the column address line φ_(vJ) are driven to High-level. Then, the clock line φ_(I) is driven to High-level. At this time, in the case of the Ith row address line driven to High-level, the thyristor P_(IJ) on the Ith row and Jth column of the matrix emits light, and in the case of the Ith row address line driven to Low-level, the thyristor P_(I0) covered by the opaque material on the Ith row and 0th column emits light. After the clock line φ^(I) is driven to Low-level in order to stop the light-emission of the thyristor on the Jth column, at least one thyristors on next (J+1) column is caused to emit light.

FIG. 4 shows a second embodiment of the two-dimensional light-emitting element array device according to the present invention. This device comprises a light-emitting element array in which a plurality of three-terminal light-emitting thyristor are arranged in an X-Y matrix of N rows×M columns (N≧1, M≧1). In the figure, the matrix of 4×4 is shown for simplicity of the drawing. In this device, anodes of all the thyristors are connected together to a clock line φ_(I) through a resistor R_(L). The gate of the thyristor P_(IJ) on the Ith row and Jth column (1≦I≦N, 1≦J≦M) of the matrix is connected to a row address line φ_(hI) of the Ith row through a resistor R_(h), and to a column address line φ_(vJ) of the Jth column through a resistor R_(v).

The gate voltage of the thyristor P_(IJ) is equal to the mean value of both the voltage of the Ith row address line φ_(hI) and the voltage of the Jth column address line φ_(hJ), if the values of two resistors R_(h), R_(v) are selected to be equal. Therefore, when both the Ith row address line φ_(hI) and the Jth column address line φ_(vJ) are driven to Low-level and other row address lines and column address lines are driven to High-level, the gate voltage of the thyristor P_(IJ) goes to the lowest voltage such as 0 volt. Therefore, when the clock line φ_(I) is driven to High-level, the thyristor P_(IJ) emits light and other thyristors do not emit light. In this manner, only one thyristor may emit light among the thyristors arranged in the X-Y matrix at the same time.

FIG. 5 shows a third embodiment of the two-dimensional light-emitting element array device according to the present invention. This device comprises a light-emitting element array of N×M matrix which is same as the array shown in FIG. 3., a three-phase driving self-scanning type transfer element array 16 for driving the row address lines φ_(h1), φ_(h2), φ_(h3), . . . of the light-emitting element array, and a two-phase driving self-scanning type transfer element array 18 for driving the column address lines φ_(v1), φ_(v2), φ_(v3), . . . of the light-emitting element array. These self-scanning type transfer element array 16 and 18 are the same type of array as disclosed in Japanese Patent No. 2577034 issued to the present applicant, the content of this Japanese patent being incorporated herein by reference.

In the three-phase driving self-scanning type transfer element array 16, a plurality of transfer elements connected to the same transfer clock line may be turned-on at the same time. On the other hand, in the two-phase driving self-scanning type transfer element array 18, only one transfer element connected to the same transfer clock line may be turned-on at the same time.

The structure of the two-phase driving self-scanning type transfer element array 18 will now be explained. Transfer elements T_(v1), T_(v2), T_(v3), . . . each thereof consisting of a three-terminal light-emitting thyristor are arranged in one dimension, i.e., in X-direction. The gates of adjacent transfer elements are interconnected through a diode D. Each gate of the transfer element is connected to a supply voltage φ_(GA) through a corresponding load resistor R. The gate of the first transfer element T_(v1) is connected to a start pulse line φ_(vS). Respective anodes of the transfer elements are alternately connected to two-phase transfer clock lines φ_(vc1), φ_(vc2). Respective cathodes of the transfer elements are connected to the ground. Since the transfer elements consist of light-emitting thyristors, light-emitting portion thereof must be covered by an opaque material so that light does not come through to the surface of the device. Each gate of transfer elements in the array 18 is also connected to a corresponding column address line of the Jth column (1≦J≦M) of the light-emitting element array.

When the transfer clock line φ_(vc1) is driven to High-level, and thus the transfer element T_(vJ) on the Jth column is turned-on, the gate voltage of this transfer element is reduced from the supply voltage φ_(GA), e.g., 5 volts to about 0 volt. The voltage reducing effect works to the gate of the adjacent transfer element T_(v(J+1)) on the right, setting the voltage of that gate to about 1 volt, i.e., a forward rise voltage of the thyristor. On the contrary, the voltage reducing effect does not work to the gate of the adjacent transfer element T_(v(J−1)) on the left, because the diode D is reverse-biased.

The turn-on voltage of the transfer elements is approximated to the gate voltage plus the diffusion potential of the PN junction (about 1 volt). Therefore, if the voltage of the transfer clock line φ_(vc2) is set to the voltage which is higher than about 2 volts which is necessary voltage for turning-on the transfer element T_(v(J+1)) and lower than about 4 volts which is necessary voltage for turning-on the transfer element T_(v(J+3)), only the transfer element T_(v(J+1)) may be turned-on while keeping other transfer elements turned-off. Thus, ON state may be transferred by setting alternately the voltages of the two transfer clock lines φ_(vc1) and φ_(vc2) to High-level.

The structure of the three-phase driving self-scanning type transfer element array 16 is essentially the same as that of the two-phase driving self-scanning type transfer element array 18, except that the transfer clock lines are three-phase, i.e., φ_(hc1), φ_(hc2) and φ_(hc3), and a current-limiting resistor r is inserted between an anode of each transfer element and the corresponding transfer clock line. As shown in FIG. 5, each anode of transfer elements T_(h1), T_(h2), T_(h3), . . . is connected to each transfer clock line φ_(hc1), φ_(h2) and φ_(hc3) in a repeating manner, the gate of the first transfer element T_(h1) is connected to a start clock line φ_(hS), and the gates of all the transfer elements are connected to the common supply voltage φ_(GA) through a corresponding load resistor R, respectively.

The transfer elements of the array 16 are constituted by light-emitting thyristors as in the case of the array 18, so that the light-emitting portions must be covered by a opaque material not so as to leak light.

The light-emitting thyristors T_(h1), T_(h4), T_(h7), T_(h10), . . . are connected to the corresponding row address line φ_(h1), φ_(h2), φ_(h3), φ_(h4) . . . , respectively.

As stated hereinbefore, the self-scanning type transfer element array 16 operate in such a manner that a plurality of light-emitting thyristors connected to the same transfer clock line may be turned-on at the same time. When the transfer clock line φ_(hc1) connected to the transfer element T_(h1) is at High-level, if the start clock line φ_(hS) is at Low-level, then the transfer element T_(h1) is turned-on, and if φ_(hS) is at High-level, then T_(h1) is not turned-on. When the transfer clock line φ_(hc2), φ_(hc3), φ_(hc1) are driven to High-level in this sequence, ON/OFF state is transferred to the transfer element T_(h4). At this time, depending on Low-level/High-level state of the start clock line φ_(hS), ON/OFF state of the transfer element T_(h1) is determined. Thus, Low-level/High-level information which is inputted to the start clock line φ_(hS) is developed on the self-scanning type transfer element array 16 as ON/OFF states of the transfer elements.

The operation of the present embodiment will now be described. First, the transfer element T_(v1) of the array 18 is caused to be turned-on by setting the start clock line φ_(vS) to Low-level and the transfer clock line φ_(vc1) to High-level. Thereby, the first column address line φ_(v1) of the first column goes to Low-level.

Next, the light-emission information (ON/OFF information) for the thyristors on the first column of the matrix is inputted to the self-scanning type transfer element array 16, i.e., Low-level/High-level information is added to the start clock line φ_(hS).

FIG. 6 shows the timing of the start clock line φ_(hS) and the transfer clock lines φ_(hc1), φ_(hc2), φ_(hc3) in order that the light on/off state of the light-emitting elements P₁₁, P₂₁, P₃₁, P₄₁, and P₅₁ (not shown) on the first column are intended to be “on, off, on, off, off”. For this light on/off state, the row address lines φ_(h1), φ_(h2), φ_(h3), . . . must be High-, Low-, High-, Low-, Low-levels, respectively. Since the gate of the transfer element goes to Low-level when it is turned-on, the transfer elements T_(h1), T_(h4), T_(h7), T_(h10), and T_(h13) (not shown) must be turned-off, -on, -off, -on, and -on, respectively. For this purpose, Low-level/High-level information added to the start clock line φ_(hS) must be L, L, H, L, H (L and H mean Low-level and High-level, respectively) as shown in FIG. 6.

Thus, when the clock line φ_(I) is driven to High-level after the light-emission information is inputted into the self-scanning transfer element array 16, the on, off, on, off, and off state of the light-emitting elements P₁₁, P₂₁, P₃₁, . . . is realized. When the clock line φ_(I) is driven to Low-level, ON state is transferred to the adjacent transfer element T_(v2) in the self-scanning type transfer element array 18. Next, the light-emission information for the second column of light-emitting elements is inputted into the array 16, and the clock line φ_(I) is driven to High-level and then to Low-level, as a result, the on, off state of the light-emitting element P₁₂, P₂₂, P₃₂ . . . is realized. Such an operation as described above is repeated to cause the thyristors in the light-emitting element array to emit light.

While two-phase and three-phase self-scanning type transfer element array are used in the third embodiment, any transfer element array of two or more phases may be used.

FIG. 7 shows the fourth embodiment of the two-dimensional light-emitting array device. This device comprises a light-emitting element array of N×M matrix which is the same as the array shown in FIG. 4., a two-phase driving self-scanning type transfer element array 20 for driving the column address lines φ_(v1), φ_(v2), φ_(v3), . . . of the light-emitting element array, and a two-phase driving self-scanning type transfer element array 22 for driving the row address lines φ_(h1), φ_(h2), φ_(h3), . . . of the light-emitting element array. These self-scanning type transfer element array 20 and 22 are the same as the array 18 shown in FIG. 5. Since the operation of those two-phase transfer element arrays 20, 22 is the same as that of the array 18, the further explanation will be omitted.

In this embodiment, the self-scanning type transfer element array 20 is self-scanned so that the column address line φ_(v1), φ_(v2), φ_(v3), . . . is driven to Low-level in turn. When one column address line is driven to Low-level, the self-scanning type transfer element array 22 is self-scanned so that the row address lines φ_(h1), φ_(h2), φ_(h3), . . . is driven to Low-level in turn. Then, the clock line φ_(I) is driven to High-level at the timing when the thyristor is caused to emit light.

While the invention has been described in terms of preferred embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims. 

What is claimed is:
 1. A two-dimensional light-emitting element array device, comprising: a light-emitting element array in which a plurality of three-terminal light-emitting thyristors are arranged in X-Y matrix of N rows×M columns (N≧1, M≧0); a plurality of row lines to each thereof an anode of the thyristor on a corresponding row of the matrix is connected; one clock line to which all the row lines are connected; a plurality of row address lines to each thereof a gate of the thyristor on a corresponding row and a 0th column of the matrix is connected; and a plurality of column address lines to each thereof a gate of the thyristor on a corresponding column of 1st-Mth columns of the matrix is connected; wherein light-emitting portions of all the thyristors on the 0th column are covered by an opaque material.
 2. A method for driving a two-dimensional light-emitting element array device of claim 1, wherein one or more thyristors on a Jth column (1≦J≦M) of the matrix is intended to emit light, comprising the steps of: driving a row address line to High-level, which is of a corresponding row of the matrix on which a thyristor to be emitted light is, while driving other row address lines to Low-level; driving a column address line on the Jth column to Low-level, while driving other column address lines to High-level; and driving the clock line to High-level.
 3. A two-dimensional light-emitting element array device, comprising: a light-emitting element array in which a plurality of three-terminal light-emitting thyristors are arranged in X-Y matrix of N rows×M columns (N≧1, M≧0); a plurality of row lines to each thereof an anode of the thyristor on a corresponding row of the matrix is connected; one clock line to which all the row lines are connected; a plurality of row address lines to each thereof a gate of the thyristor on a corresponding row and a 0th column of the matrix is connected; a plurality of column address lines to each thereof a gate of the thyristor on a corresponding column of 1st-Mth columns of the matrix is connected; a first self-scanning type transfer element array for driving the column address lines to High-level or Low-level by self scanning thereof; and a second self-scanning type transfer element array for driving the row address lines to High-level or Low-level by self scanning thereof; wherein light-emitting portions of all the thyristors on the 0th column are covered by an opaque material.
 4. A method for driving a two-dimensional light-emitting element array device of claim 3, wherein one or more thyristors on a Jth column (1≦J≧M) of the matrix is intended to emit light, comprising the steps of: driving the column address lines in turn to High-level by the first self-scanning type transfer element array; driving one or more row address lines to High-level, while driving other row address lines to Low-level by the second self-scanning type transfer element array, when the column address line on the Jth column is driven to Low-level; and driving the clock line to High-level. 